1. Field
The following description relates to an optical image stabilizer and a camera module including the same.
2. Description of Related Art
Since a camera module mounted in a mobile device has a lens aperture smaller than that of a general camera, an amount of light entering such a camera module mounted in the mobile device is less than that of a general camera at the time of capturing an image. Therefore, camera modules mounted in the mobile device commonly have relatively slow shutter speeds in order to compensate for an insufficient amount of light therein. However, in this case, distortion of an image may be generated even with fine hand-shake, such that it may be difficult to obtain a clear image.
In order to suppress deterioration of the image due to the fine hand-shake and obtain a clearer image, various optical image stabilization methods have been developed. Such a method is to use an optical image stabilization (OIS) processor providing an optical hand-shake correction function.
The OIS processor may use an angular velocity sensor to sense fine vibrations caused by movement such as hand-shake and calibrate an optical path of the camera module by a mechanical method, based on the sensed vibrations, to correct image distortion. However, since an output of the angular velocity sensor includes a bias offset to correct a bias error, in a case in which an angular position is calculated by integrating an angular velocity signal obtained by the angular velocity sensor, the bias offset is integrated therewith, such that errors of the angular position may be amplified over time.
Therefore, the angular velocity signal is quantized and subsequently passes through a high pass filter (HPF), such that the bias offset of the angular velocity signal may be removed, as disclosed in Japanese Patent Publication No. 2012-48138.